The Brexit settlement for Northern Ireland is "not working at the moment," U.K. Cabinet Office Minister Michael Gove said, as he accused the EU of having opened "Pandora's box" when it sought to block coronavirus vaccines entering the U.K. at the end of last month.

Speaking at a House of Commons committee, Gove described the EU's aborted decision to trigger Article 16 of the Northern Ireland protocol, a special post-Brexit border arrangement intended to preserve the Good Friday peace agreement, as "a moment when trust was eroded."

The European Commission rapidly reversed its decision to invoke the emergency measure following a diplomatic outcry from ministers in the U.K., Ireland and Northern Ireland. However, Gove said he remained concerned about the precedent that had been set.

“Even though the EU said they would not be invoking Article 16 on this occasion, they haven’t given a solemn and binding undertaking never to do so," he said. "The Pandora’s box has been opened and that is concerning.”

European Commission Vice President Maroš Šefčovič, Gove's opposite number on the joint committee established to oversee the protocol, is due in London Thursday for further talks on the border, Gove said.

Food supplies and online orders entering Northern Ireland have been subject to delays since the protocol — in which the U.K. agreed to new checks on goods crossing the Irish Sea border — came into effect on January 1. Port staff have also been subject to threats, leading to the suspension of some checks.

Gove said the protocol "can be made to work" with "refinement." The U.K. already called for "grace periods" which limit checks on some goods, such as those moved by major supermarkets, to be extended until 2023.